Conventionally, when base rocks are to be dug (ripping operation) by a construction machine such as a bulldozer, a parallel link type shock ripper device 1 is mounted on a rear 2 of the vehicle, as shown in FIG. 7. A shank 8 is forced into the base rock by the depressing force generated by the weight of the bulldozer. The base rock is broken up by utilizing the towing force of the bulldozer and the hydraulic force of a tilt cylinder 5. The ability with which the bulldozer breaks up the base rock is substantially proportional to the weight of the vehicle. Thus, the hardness of the base rocks at the operation site is investigated beforehand, and a vehicle which suits the operation condition is selected.
When hard rocks that cannot be broken up by such an operation exist, they are cracked by utilizing the blows of a hydraulic breaker 10 mounted on the ripper device 1 to facilitate breaking (as is disclosed in Japanese Utility Model Laid-Open No. 35068/1987). The blows F given by the hydraulic breaker 10 are transferred from an impact receiving surface 8b of the shank 8 to the base rock through a ripper point 17 provided at one end of the shank 8, as shown in FIG. 8. However, since a shank rotating shaft 8a provided at the other end of the shank 8 is pivotally supported on an arm 6, the ripper point 17 revolves in the form of an arc around the shank rotating shaft 8a. In consequence, the blow F exerted on the base rock is reduced, and the function of the hydraulic breaker 10 cannot be fully utilized. As a result, the base rock cannot be broken regularly, and the vehicle jolts considerably when it travels in reverse, providing an uncomfortable ride. Furthermore, since the ripper point 17 cannot be forced very far into the rock, the ripper point 17 slips often, increasing wear of the ripper point. Also, the tracked vehicles slip often, increasing wear or damage thereof.
In view of the aforementioned problem, an object of the present invention is to provide a direct driven shock ripper device which is capable of efficiently transferring blows of a hydraulic breaker to a base rock.